Sunday, 28 September 2014

Tim Tyler: Cultural kin selection

This is a big and important topic which must be condensed for this kind of format - so this is a "firehose" presentation on the topic.

Nepotism is a common phenomena in nature. It has long been understood that evolutionary theory could help to explain why organisms help their relatives. However it wasn't until the 1960s that the process responsible for nepotism was formally modelled.

William Hamilton visualized the germ line of organisms as being broken up into many genes. Each gene is surrounded by many copies of itself in its relatives. It then becomes possible to ask what behaviour the gene could promote that would help the swarm of genes to propagate itself. The answer indicates that there are circumstances under which genes can favour transferring resources to other existing copies of themselves at the expense of their own direct descendants.

The theory that quantifies and explains this phenomenon is known to biologists as "kin selection".

It is a commonplace observation that cultural similarity also results in cooperative behaviour. Empirically, there's a correlation between the memes that people share and how likely they are to cooperate with one another. Memes resulting in observable markers seem particularly significant - so the uniforms worn by the military, nurses, religious orders and corporate workers are especially closely associated with cooperative behaviour. The most conventional explanation for this is known as "fictive kinship". The idea is that shared uniforms stimulate mechanisms evolved to deal with kinship at the level of DNA genes. The kinship involved is not real blood kinship, but rather has been faked by leaders of these groups for their own ends - thus the term "fictive kinship".

However, another explanation invokes cultural kinship. The theory of kin selection is not confined to DNA genes. It can equally be applied to memes. Shared memes often result in cooperation in the same way that shared genes do. Like DNA fragments, memes are frequently surrounded by a swarm of copies of themselves. Again, it is possible to ask what behaviour promoted by the meme would serve to promote the propagation of the swarm of copies surrounding it. Again the answer indicates that memes will sometimes sacrifice themselves to promote the propagation of other copies of themselves. The theory that explains this is called "cultural kin selection" - and that is what this video is about.

Cultural kinship helps to explain why nurses wear similar uniforms to each other and cooperate with one another. Shared memes help to explain explains why your computer and your printer peacefully cooperate to print documents. Nuns form cultural "sisterhoods" and monks form cultural "brotherhoods". Their lives are often dominated by the memes they share, and their mission in life is typically to spread these memes to others. Patriotism memes illustrate that memes can sacrifice themselves if it helps copies of the same meme in others to survive. Cultural kinship is an essential tool for understanding how memes propagate the modern world.

In the organic realm close kinship sometimes results in eusociality - where a fertile queen is surrounded by multiple sterile workers. We see the same phenomenon in culture - banks are surrounded by millions of identical coins and bills. These are not themselves copied. Indeed there are cultural adaptations which actively prevent counterfeit copies from being made. The function of these multiple identical cultural entities is to divert resources to their cultural parents in the bank. Another familiar case involves digital books. these exist in multiple identical copies. However most of the copies themselves are not fertile. Digital rights management and legal threats are used to try and prevent them from being copied.

Sterile worker forms are one of the tell-tale signatures of kin selection. The other one is self-sacrifice. Memes that spread despite apparently aiding their personal destruction could be being spread via cultural kin selection. Patriotism memes and suicide bomber memes are possible examples.

Kin selection is famously associated with Hamilton's rule. To briefly recap, Hamilton's rule measures the cost to a donor and the benefit of a recipient associated with a behaviour and the relatedness between the actors. It then asserts that the behaviour can be favoured by kin selection if the benefit is greater than the cost multiplied by the relatedness. This simplified model of kin selection has proved to be quite useful in the organic domain. However its utility depends partly on the ease of measuring relatedness. In the organic realm, there's a simple approximation that can be used: parents are related to offspring by one half, cousins by one eighth - and so forth. Ultimately these fractions come from meiosis. However, there's not really a direct equivalent of meiosis in cultural evolution - which makes it harder to apply Hamilton's rule. Humans don't share half their memes with their parents and one eighth of their memes with their cousins. However they do typically share more memes with their parents than with their cousins. If you consider the topic of relatedness between artifacts, measuring relatedness often becomes easier - because it is easier to measure memes in artifacts than it is in brains.

It has long been understood by anthropologists that "cultural kinship" exists in humans. Humans treat all kinds of people who are not blood relatives as though they are honorary family members. Churches in particular are full of father, mother, brother and sister relationships which do not reflect any form of blood-based kinship. However, most anthropologists have historically had a weak understanding of evolution - and have reacted with hostility to the efforts of biologists to enter their territory.Many anthropologists seem to associate evolutionary theory with racism and eugenics. Cultural kinship has been regarded within anthropology as evidence that Darwinian evolutionary theory applies only weakly to human behaviour - and that cultural forces are more important. This wilful ignorance of evolution meant that they failed to find a coherent theoretical foundation that would account for their observations.

Cultural kin selection casts new light on this topic. On the one hand it shows that the anthropologists were correct to emphasize the significance of cultural kinship. However, on the other hand, it also shows that the evolutionists were right on target with their Darwinism. Cultural kin selection neatly explains the importance of cultural kinship in humans from within an evolutionary framework that includes the concept of shared memes.

Lastly, cultural kinship offers an intriguing glimpse of scientific history repeating itself. In the 1960s, group selection was a popular theory - before kin selection displaced it. Now, 50 years later, cultural group selection is a popular theory. However, kin selection is much better than group selection. It puts an entirely appropriate emphasis on the significance of close kinship, it more strongly encourages quantification and is less strongly associated with junk science. Group selection has proven itself to be a confusing and misleading tool for understanding essentially the same set of phenomena that kin selection explains. Consequently, the same dynamics that we saw in the 1960s are now evident again. A similar sequence of events seems to be playing itself out with cultural group selection and cultural kin selection. This case of history repeating itself in science gives us an interesting opportunity to quantify the scientific lag that cultural evolutionary theory suffers from. By this metric, it's about 50 years behind mainstream evolutionary theory.

There's a lot more to say about this topic - far more than can possibly fit into this video. Search online for "cultural kin selection" for much more information about this subject area.